1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device, and more particularly to a pattern forming method, a reticle correcting method, and reticle pattern data correcting method for a lithography process.
2. Description of the Related Art
With miniaturization of a semiconductor device, forming randomly arranged fine patterns, e.g., contact holes, has become difficult by a conventional lithography technology. That is because, comparing a pattern without periodic properties with a periodic pattern, a resolution of lithography is lower and a process margin is also narrower in the pattern without periodic properties.
A method of forming randomly arranged contact hole patterns is disclosed, for example, in a specification of U.S. Pat. No. 6,664,011B2, “Semiconductor Foundry, Lithography, and Patterns”, Proceedings of SPIE 4688, pp. 31-44, 2002, by B. J. Lin, and “Low Proximity Contact Holes Formation by Using Double Exposure Technology (DET)”, Proceedings of SPIE, Vol. 5040, pp. 1241-1246, 2003, by C. Chang et. al. The disclosed method is called a pack and cover process. FIGS. 1A and 1B are views for explaining the pack and cover process, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view. As depicted in the drawings, according to this method, photosensitive resin films 10 and 20 (which will be referred to as resist films, hereinafter) doubly formed on a processing film 5 provided above a semiconductor substrate 1 are used to form fine contact hole patterns 34 in a desired arrangement on the processing film 5.
Specifically, first, periodic fine contact hole patterns 14 composed of the first resist film 10 are formed on the processing film 5. That is because periodic patterns have advantages as compared with random patterns. One of the advantages is that a pattern having a smaller dimension can be formed with a wider focus margin. Then, the second resist film 20 is formed on the entire surface of the first resist film 10, and a selective opening resist pattern 24 to open only desired contact holes is formed. In this manner, the randomly arranged desired fine contact hole patterns 34 can be opened.
In reality, however, when the second resist film 20 is formed, the first periodic contact hole pattern 14 is filled with the second resist film 20. When the selective opening resist pattern 24 composed of the second resist film 20 is formed in such a state, as shown in FIGS. 1A and 1B, a part of the second resist film 20′ may remain on an inner wall of the periodic contact hole pattern 34 at the time of development of the selective opening resist pattern 24. Therefore, a final dimension of the contact hole pattern 34 after forming the selective opening resist pattern 24 may be smaller than a dimension of the original periodic contact hole pattern 14.
Further, the final dimension of the actually opened contact hole pattern 34 is affected by types of the selective opening pattern, e.g., a single hole, a twin hole, or the like. Furthermore, it is also affected by a dimension of the selective opening pattern irrespective of the types of the selective opening patterns. That is, when the selective opening resist pattern 24 becomes smaller, the final dimension of the contact hole pattern 34 becomes small disadvantageously.